Various automated systems for forming and cutting surgical suture tips exist or are known in the art. In one such machine, means for simultaneously advancing in parallel at least six separate strands of suture material, and six independent tensioners for maintaining respective parallel portions of each of the six strands at a preset tension are provided. Once a predetermined length of suture material has been advanced by the advancing means, a horizontal heater bar (positioned perpendicular to the six suture strands) is actuated by an electronically controlled solenoid which moves a planar heater bar into contact with one side of the suture strands for a predetermined dwell time. Once the predetermined dwell time has elapsed, the solenoid retracts the heater bar to its original position, and the heat exposed (or heat-stiffened) section of suture material is advanced to a cutting station. At the cutting station, the heat-stiffened section of suture material is cut at its midpoint, thereby producing a suture with two stiffened ends. Other mechanisms for forming and cutting surgical suture tips are shown in U.S. Pat. Nos. 4,832,025, 4,806,737 and 5,226,336 to Coates. The system described in the Coates patents uses convective or non-contact heating to form suture tips.
Known systems for forming and cutting surgical suture tips suffer from several drawbacks. First, such systems typically use heat to stiffen the surgical suture tips. Since the unfinished surgical suture material used by such systems is often coated, the heat applied during the tipping process may melt the coating. Once it has melted, the coating from the unfinished surgical suture material often adheres to the tipping machine, thereby compromising the machine's performance. Another drawback of known systems for forming and cutting surgical suture tips is that such systems typically produce a suture tip which lacks a substantially uniform cross-section. In addition, such systems are undesirable in that they typically cut the suture tip in an imprecise manner, thereby leaving a cut end which may be irregular or distorted in shape. From a manufacturing standpoint, suture tips having non-uniform cross-sections and/or irregular or distorted cut ends are undesirable because, among other things, such sutures are difficult to insert into needles. Finally, known systems which use heat to stiffen surgical suture tips are undesirable because such systems cannot be used with sutures formed from silk.
It is therefore an object of the present invention to provide a system for forming surgical suture tips which system does not use heat in forming the suture tips and which may be used to fuse silk.
It is a further object of the present invention to provide a surgical suture having a welded core which facilitates the easy insertion of the suture tip into a needle.
It is a further object of the present invention to provide an automated system and method for manufacturing surgical sutures having tips with welded cores.
It is a still further object of the present invention to provide an automated system and method for making surgical sutures with tips having precisely cut ends.
These and other objects and advantages of the invention will become more fully apparent from the description and claims which follow or may be learned by the practice of the invention.